1. Field of the Invention
The present invention relates to a flat bag, which is composed of foils and closed on all sides and which is filled with a thermally conducting paste or liquid.
2. Brief Description of the Background of the Invention Including Prior Art
The thinner the intermediate gap space or slot filled with air and disposed between the thermally contacting surfaces of the bodies is, the larger the heat transfer between two solid bodies. It is known to grind the surfaces planar and to polish the surfaces in order to reduce the thermal resistance between two bodies, which are in contact only for a certain time duration. If this is too expensive, then it is further known to fill the slot between the contact surfaces with a thermally conducting paste. This paste reduces the thermal resistance of the respective slots in each case based on its thermal conductivity, which is substantially higher than that of air. Thermally conducting pastes are relatively difficult to handle, since the pastes are highly viscous and behave like an adhesive. Therefore, it was attempted to improve the properties by enclosing the pastes into a bag. For example, a plastic bag is known from U.S. Pat. No. 3,586,102, which serves for the production of thermal bridges between the devices of a conductor plate and a heat dissipating plate.
A plastic bag is known from IBM Disclosure Bulletin, Volume 19, No. 8, January 1977, page 3127, which bag is filled with liquid metal. This bag again serves for the removal of heat from electrical devices to a thermal sink.
Neither thermal conductivity pastes nor bags of the kind taught by the art are suitable for reducing the thermal resistance in vertical slots with a relatively small temperature gradient. Open pastes run out of the slot in the course of time and influence the resistance in an uncontrolled fashion. In contrast, the bags have too large a volume and the plastic of the foils of the bags causes an increase of the overall thermal resistance, which cannot be neglected.